Caché ObjectScript Reference - InterSystems Documentation

Caché ObjectScript FunctionsProviding No ParametersInvoking the $LISTBUILD function with no parameters returns a list with one element whosedata value is undefined. This is not the same as a null string:SET x=$LISTBUILD()SET y=$LISTBUILD("")ZZDUMP x,yreturns:0000: 01 .0000: 02 01 ..Nesting ListsAn element of a list may itself be a list. For example, the following statement produces athree-element list whose third element is the two-element list, "Walnut,Pecan":SET X=$LISTBUILD("Apple","Pear",$LISTBUILD("Walnut","Pecan"))WRITE $LIST(X,3)Concatenating ListsThe result of concatenating two lists with the Binary Concatenate operator is another list. Forexample, the following two WRITE statements produce the same list, "A,B,C":WRITE !,$LIST($LISTBUILD("A","B")_$LISTBUILD("C"),0,-1)WRITE !,$LIST($LISTBUILD("A","B","C"),0,-1)For further details, see Operators in Using Caché ObjectScript.A null string ("") is an empty list. For example, the following two expressions each producethe same two-element list:WRITE !,$LISTBUILD("A","B")_""WRITE !,$LISTBUILD("A","B")However, the following two expressions each produce a three-element list:WRITE !,$LISTBUILD("A","B")_$LISTBUILD("")WRITE !,$LISTBUILD("A","B")_$LISTBUILD()UnicodeIf one or more characters in a list element is a wide (Unicode) character, all characters in thatelement are represented as wide characters. To insure compatibility across systems,$LISTBUILD always stores these bytes in little-endian order, regardless of the hardwareplatform. Wide characters are represented as byte strings. Therefore, when displayed usingZZDUMP, the ZZDUMP length reflects the number of bytes, not the number of Unicodecharacters.246 Caché ObjectScript Reference